The present invention relates to a system and method for controlling the movement of one or more jet engine thrust reverser components. More particularly, the present invention relates to a system and method for controlling the movement of one or more jet engine thrust reverser components during a deployment operation of the thrust reversers.
When jet-powered aircraft land, the landing gear brakes and imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required amount of distance. Thus, jet engines on most aircraft include thrust reversers to enhance the stopping power of the aircraft. When deployed, thrust reversers redirect the rearward thrust of the jet engine to a forward direction, thus decelerating the aircraft. Because the jet thrust is directed forward, the aircraft will slow down upon landing.
Various thrust reverser designs exist in the art, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. As will be discussed more fully below, each of these designs employs a different type of xe2x80x9cmoveable thrust reverser component,xe2x80x9d as that term is defined herein below.
Cascade-type thrust reversers are normally used on high-bypass ratio jet engines. This type of thrust reverser is located at the engine""s midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes positioned on the outside of the engine. The moveable thrust reverser component in this design may include several translating sleeves or cowls (xe2x80x9ctranscowlsxe2x80x9d) that are deployed to expose the cascade vanes. Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser component to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and form the rear part of the engine nacelle. Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser component. In the deployed position, these doors extend outwardly from the nacelle to redirect air flow.
The primary use of thrust reversers is, as noted above, to enhance the stopping power of the aircraft, thereby shortening the stopping distance during landing. Hence, thrust reversers are primarily deployed during the landing process. More specifically, once the aircraft has touched down, the thrust reversers are deployed to assist in slowing the aircraft. Thereafter, when the thrust reversers are no longer needed, they are returned to their original, or stowed position.
When the thrust reversers are moved to the deployed position, the transcowls or doors are moved until the actuator elements to which they are attached reach a mechanical hard stop at the end of travel. In order to prevent structural damage, the actuator elements should come to a controlled stop against the mechanical hard stop. One problem associated with electromechanical thrust reverser systems in which the motive force for moving the thrust reversers is provided by electric motors, is that the aerodynamic loads imposed during aircraft landing tend, after a certain point during the deployment process, to accelerate the motors. Thus, if power is removed from the motors too soon before the actuator elements reach their mechanical hard stop, the motors will xe2x80x9cfree-wheel,xe2x80x9d being driven by the aerodynamic loads, up to speeds that may cause system damage. Conversely, if power is supplied to the motor until the actuator elements hit the mechanical hard stop, the motor will try to drive the actuator elements past the hard stops and impose unwanted mechanical and electrical loads on the system.
Hence, there is a need for a system and method for controlling the deployment of one or more jet engine thrust reversers that solves one or more of the problems identified above. Namely, a system and method for controlling jet engine thrust reverser deployment that avoids one or more of the following: unwanted motor accelerations due to aerodynamic loads imposed during thrust reverser deployment operations, unwanted motor actuation too near to or after the hard stops have been reached to avoid unwanted mechanical and electrical loads and related system damage.
The present invention provides a system and method for controlling jet engine thrust reverser deployment that avoids unwanted mechanical and electrical loads, and/or thrust reverser system damage. Specifically, and by the way of example only, the rotational speed of a motor that is provided for moving the thrust reversers to the deployed position is continuously sensed and compared to predetermined rotational motor speed values. The speed that the motor is controlled to rotate at is reduced from a non-zero value to zero when the thrust reversers reach a predetermined position. When the sensed rotational speed is at or above a first, upper predetermined rotational speed, power is applied to control the speed of the motor to decelerate the motor to zero. When the sensed rotational speed is at or below a second, lower predetermined rotational speed, power to the motor is removed. When power to the motor is removed, if the thrust reversers are not against their mechanical stops, the aiding aero loads will cause the motor to accelerate to, or above, the first predetermined rotational speed. This will cause power to be supplied to the motor, thereby causing it to decelerate toward the second predetermined speed. When the rotational speed reaches the second predetermined speed, the motor will again be deenergized. Thus, when the thrust reversers reach the predetermined position, the thrust reversers will limit cycle between the two predetermined speed limits until the mechanical stop is reached in a controlled manner.
In one aspect of the present invention, a jet engine thrust reverser control system includes an electric motor, one or more moveable thrust reverser components, a speed sensor, and a controller circuit. The moveable thrust reverser components are coupled to the motor, and are moveable between a stowed position and a deployed position. The speed sensor is operable to sense at least a rotational speed of the motor and produce a speed feedback signal. The controller circuit is coupled to receive the speed feedback signal and is operable, in response thereto, to energize and deenergize the motor when the rotational speed of the motor is, respectively, at or above a first predetermined rotational speed and at or below a second predetermined rotational speed.
In another aspect of the present invention, a jet engine thrust reverser control system includes moving means, speed sensing means, and controller means. The moving means is for moving one or more moveable thrust reverser components to at least a deployed position. The speed sensing means is for sensing a rotational speed of the moving means. The controller means is for (i) energizing the moving means when the speed sensing means senses that the rotational speed of the moving means is at or above a first predetermined rotational speed and (ii) deenergizing the moving means when the speed sensing means senses that the rotational speed of the moving means is at or below a second predetermined rotational.
In still another aspect of the present invention, a method of controlling a jet engine thrust reverser system includes powering a motive force providing component to move one or more moveable thrust reverser components toward at least a deployed position. At least a movement speed of the motive force providing component is sensed. Power to the motive force providing component is selectively applied and removed in response to the sensed movement speed of the motive force providing component being, respectively, at or above a first predetermined movement speed and at or below a second predetermined movement speed.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.